The sample handling apparatuses according to prior art can be classified according to a main feature:
One group comprises the apparatuses for analyses wherein each sample is analyzed in a different vessel, the other group comprises the apparatuses wherein the cyclically changed samples are analyzed in one and the same vessel (e.g. a section of the tube) either after only removing the previously analyzed sample or after cleaning the vessel following the removing of the previous sample.
The first group is disadvantageous in so far that each vessel shall either be thrown away or picked out of the analyzer channel, specially cleaned and again incorporated into the analyzer channel. The process is also more complicated because the analyzing means such as the electrode used for the polarographic analysis shall be moved from the one vessel into the other one and also the electrodes shall be cleaned after each cycle. The PARC Model 316 Automatic Cell Sequencer (Princeton Applied Research; PAR) belongs to this group.
The other group is disadvantageous in so far that it can not generally be used, e.g. samples for polarographic analysis can not be handled by such apparatuses. The Auto Analyzer (manufactured by Technicon Corp.) belongs to this group.